He went to ask a question; she silenced him with a gesture. And explained.

‘About four hundred years ago Zugarramurdi was the centre of a huge witch craze. A French witch hunter, Pierre De Lancre, became convinced that…’ Amy grimaced. ‘He decided that all Basques were essentially witches. Because the Basques were so different, the easily identifiable minority. They were the other.’

‘You mean…like the Jews?’

‘Of course. It began around…1610. A Basque girl who had been working away from home, in Ciboure, near Saint Jean de Luz on the coast, she came back to her village in the hills. To Zugarramurdi.’

The reflected light of the stream bounced off the cavern ceiling. Stalactites pierced the emptiness.

‘The young woman’s name was Maria de Ximildegui. She began to denounce her friends and relatives – as witches. The local priests called in the Inquisition. Children were dragged from their families and interrogated. The kids started to report nightmares, dreams of naked greased-up witches who took them on strange flights, to the Devil’s sabbat.

‘Satan would appear as a huge billygoat, walking on his hind legs. He had intercourse with the women and children. He has, apparently, a very thick and icy black penis. Afterwards he would mark them on the forehead with his claw. The infamous marks of the Devil. Showing that he had possessed them.’

Amy stared at David, deadpan. He didn’t know what to say; whether to laugh or protest. She continued the story, her voice echoing softly in the cavern. ‘And so the craze began. The priests reported their findings, and the witch panic spread down the valley, into Elizondo, Lesaka, San Sebastian. Thousands were arrested, David, literally thousands of women, men, children…And then the priests went to work, putting people to the rack, pricking them for blood, torturing everyone.’

David was trying not to think about her scar. He said: ‘But…they did the same across Europe, right, it wasn’t that unusual? Around that time. It was like Salem, it was just a witch craze. No?’

‘No. Witch crazes were unknown on this scale, it was maybe the worst craze in Europe. They called it the Basque Dream Epidemic. The Inquisition mutilated hundreds. Dozens were lynched by villagers. Five were officially burned to death at Logrono.’

‘And De Lancre?’

Amy was staring into the grey cavern light. ‘De Lancre was even more efficient than the Inquisition. As I said, he was obsessed: he thought that all Basques were witches, an evil race to be exterminated. He burned hundreds, maybe more. It was a holocaust. Just over there, in Iparralde. The land beyond.’

She gestured at the little brook. ‘They still call this the stream of Hell. The irony of it all is that De Lancre was Basque. A self-hater.’

Her words dwindled away. David was about to ask another question, but his half-formed thoughts were crushed. By a very deep voice. Echoing.

‘Epa.’

He swivelled.

Miguel. Standing there. At the entrance to the witch’s cave.

David glanced left and right, rapidly calculating. The only descent from the rockshelf – further into the caves, or towards the light of the entrance – took them directly past Miguel. They were trapped.

‘Epa.’

David knew this one word of Basque. Hello. The terrorist’s smile was languid yet angry; his gun was pointing their way.

‘Euzkaraz badakisu? Ah no. Of course. You Americans only speak one language. Let me explain…in more intimacy.’

The tall Basque paced along the rocky ledge – the gun trained on them all the time. He slowed as he approached – and turned. David realized Miguel had an accomplice: following behind was a short, thickset man. Miguel gestured a request.

‘Enoka? La cuerda…’

The accomplice had a lauburu tattooed on his hand. And the same tattooed hand was carrying a rope. The short man, Enoka, came forward.

David shot a desperate glance at Amy.

They already had a rope? It was like they had been preparing.

The accomplice, Enoka, set to work. Tying Amy and David by the hands, behind their backs – while they sat there, mute and immobile, subdued by the terrorist’s gun. In a few seconds they had been trussed like dumb animals, headed for the slaughterhouse.

Then Miguel spoke, with a sad and frowning passion. His shadow was long on the cave roof, cast by the flickering light off the stream.

‘You know, you drive very well, Martinez. Very good. Very impressive. But you still don’t really understand these hills. You do not understand this place. Our language. You cannot understand that. Hikuntzta ez da nahikoa! Is it not so?’

Miguel half-smiled, and gazed around him at the cavern, his words resonant in the emptiness.

‘I told you what would happen when I found you again. And now I find you. In the witch’s cave! Of all places. The little witch and her big Gascon friend. Appropriate.’ He turned. ‘Remember, Amy? Our marvellous picnic supper?’

He was stooping now, looking very closely at Amy. David realized, with disgust, that he was actually stroking Amy’s face with the muzzle of the gun. Stroking her.

‘Mmm. Amy? Didn’t we? Remember the excellent blood sausage. The tripota. Your sweet marmatiko.’

She said nothing. He persisted.

‘Didn’t we have sex here? Or was that some other cave? It was here, wasn’t it? I forget.’

Her face was averted, but the killer was using the muzzle of the gun to tilt her chin, forcing her to look at him. He was quietly smiling. She was scowling. He was smiling.

And now she was smiling.

David stared, aghast.

Amy was looking up, smilingly, almost lasciviously, as Miguel murmured:

‘You know that I am going to kill him, don’t you?’

She nodded.

‘Yes.’

‘In that case, Amy, shall we have our fun first?’

She nodded again; he leaned very close:

‘Dantzatu nahi al duzu nirekin. Before we kill him.’

‘Yes,’ she agreed. ‘Please yes? Fuck me here. Fuck me like before.’

Miguel laughed. A sad and gluttonous laugh. The terror iced David’s veins with tiny crystals of grief. What was happening?

Again the terrorist traced a line from Amy’s ear, to her lips, with the metal of the gunpoint – like a surgeon practising his incision, or a butcher marking out a fillet. Then he turned to his accomplice, skulking in the shadows.

‘Enoka. Vaya, Adiós!’

The squat little man scuttled away, an expression of relief in his gait. David looked from Miguel to Amy, to Miguel again. Searching their faces. His heart was cold with the horror.

Amy was still smiling, upwards, smiling at the terrorist: submissive, needy and desirous. The twitch in the terrorist’s eye was subtle. More obvious was the erection in Miguel’s khaki trousers.

Fear and disgust suffused David’s thoughts. He didn’t even want to look at Amy. How could she do this? Was it all some terrible joke on him? Was she just saving herself? Or did she really want Miguel? Was this some strange psychosexual game the two of them were playing – and he was the necessary spectator?

His heartbeat juddered with anger – and contempt – and inadequacy.

Enoka had disappeared along the rocky passage. They were alone. Miguel and Amy – and David. The terrorist was unlashing Amy’s hands. Immediately she was free, she reached for Miguel; she was unbelting his trousers, pulling them down, and then tugging at his shirt; she was kissing him under his half shaven chin, and caressing his jawline, like a concubine soliciting a sultan for a night of love. A witch imploring the goat for his favours.

David turned away, nauseated. He didn’t want to watch; he was stuck here, tied up, he would have to listen, but he didn’t have to watch.

A deep voice echoed across. ‘You!’

He opened his eyes.

Miguel was on top of Amy, the great tall figure arched over the small young woman, like a dark roof. But he was looking at David, and the gun was still in his hand.